The present invention is generally concerned with apparatus for protecting an operator of an industrial vehicle, and more particularly with falling object protective structures for vehicles such as compacting vehicles.
It is known in the art of industrial vehicles to provide a structure or apparatus for protecting the operators of such vehicles from injuries caused by falling objects and/or from the vehicle "rolling over". Examples of industrial vehicles including protection apparatus may be found in U.S. Pat. No. 2,911,232 of Hastings, Jr. et al., concerning an overhead guard for an industrial lift truck; U.S. Pat. No. 4,055,262 of Bauer et al., concerning a loader main frame for a skid steer loader; U.S. Pat. No. 4,065,167 of Wright, concerning a safety enclosure for a mining machine; and U.S. Pat. No. 4,095,839 of Lawrence et al., concerning a protective structure for a hydraulic excavator.
Certain industrial equipment include a "Roll Over Protective Structure" ("ROPS") device. Such devices generally consist of a structural framework capable of protecting a vehicle operator in the event that the vehicle "roll-overs", preferably in accordance with criteria established by the Society of Automotive Engineers (SAE) (i.e., ROPS protection). Further, some industrial vehicles include a ROPS device in combination with structural framework covered by a protective member to provide protection from falling objects. These devices are commonly referred to as Falling Object Protective Structures ("FOPS") and have to meet other stringent SAE criteria in order for the vehicle to be FOPS certified. Such FOPS or ROPS devices are generally provided on compacting vehicles or "compactors", as depicted for example, in U.S. Pat. No. 5,719,338 of Magalski et al.
One problem that occurs when operating many types of industrial vehicles is that noise is generated within the operator station of the vehicle, which may arise from such sources as the engines and/or motors that power movement of the vehicle or from other movable components (e.g., pumps) that function on the vehicle. For many types of vehicles, panels or layers of acoustic foam, generally of a thickness of several inches, have been used for deaden such sound to acceptable levels. However, certain industrial vehicles, such as compactors having roller drums which include vibrating mechanisms, generate low frequency noise. To attempt to deaden low frequency noise with acoustic foam would require a foam thickness measured in feet rather than inches. Thus, acoustic foam is not useful for reducing low frequency noise radiation and reflection arising within these types of industrial vehicles.